武汉鹦鹉洲长江大桥上部结构施工监控技术

摘要

武汉鹦鹉洲长江大桥主桥为(200+2×850+200)m三塔钢—混凝土结合梁悬索桥.为保证该桥的成桥线形和结构受力安全满足设计要求,主缆架设时,提出了考虑温度、跨度和塔顶高程影响的基准索股跨中位置参数影响公式,并采用索股分层定位技术架设一般索股;吊索无应力下料长度计算结果采用正装和倒拆2种计算手段相互验证;加劲梁采用4台缆载吊机,按照“从两中跨靠近中塔开始架设,而后再从边塔向边墩、跨中方向架设”的顺序吊装;混凝土桥面板采用“工厂预制、桥上结合”的方式施工;在加劲梁所有梁段就位、节段间正式连接后,再浇筑混凝土湿接缝;在两主跨各吊装27个加劲梁节段后,主索鞍共分6次顶推到位.采取以上监控技术后,该桥的成桥线形及桥塔偏位均满足要求.%The main bridge of the Yingwuzhou Changjiang River Bridge in Wuhan is a threetower steel and concrete composite girder suspension bridge with span arrangement (200+2 ×850 +200) m.To ensure that the geometric shapes and structural force safety of the bridge at the completed bridge stage could meet the design requirements,for the erection of the main cables of the bridge,the influence formula for the midspan location parameters of the datum strands considering the influences of the temperatures,span length and tower top elevation was provided.The general strands of the cables were erected,using the technique of positioning the strands in layers.The calculations of the unstressed cutting length of the suspenders were checked mutually,using the two means of the forward installation and inverse removal calculation.The segments of the stiffening girder were hoisted and installed,using the 4 cable-supported cranes in the sequence starting form the vicinity of the middle tower of the two central spans and then from the side towers to the side piers and midspan of the bridge.The concrete deck slabs were constructed in a way of precasting the slabs in factory and making the slabs and steel girder composite on the bridge in field.At the time all segments of the stiffening girder were installed in place and the segments were well connected,the concrete wet joints were cast.After each 27 segments of the stiffening girder of the two central spans were hoisted and installed,the tower saddles were then pushed in place in 6 times.With the application of all the monitoring techniques mentioned above,the geometric shapes and the offsetting of the towers of the bridge at the completed bridge stage could meet the design requirements.